Screw driver



Dec. 16, 1958 R. M. VAUGHN SCREW DRIVER Filed Feb. 21, 1957 ENTOR.

INV RUDOLPH M. VAUGHN BY W v AmaJ ATTORNEYS United States Patent SCREW DRIVER Rudolph M. Vaughn, Santa Ana, Calif. Application February 21, 1957, Serial No. 641,748

3 Claims. 01. 145-50) This invention relates generally to screw drivers, and more particularly to an improved screw driver. by which Ialn eixtremely high torque may be applied to slotted screw ea s. r

This invention constitutes a'continuatio'n in part of my co-p'ending U. S. application, SerialNo. 525,007, file July 18, 1955 and entitled Screw Driver, now U. S. Patent No. 2,808,087, which application is in turn a divisional applicationfrom my then co-pending application Serial slot described in my above referred to issued Patent Num-v bers 2,745,120 and 2,677,985.

In the case of the ordinary type of slotted screw head incorporating straight slot walls to receive the screw driver, the driving end of the driver mustjordinarily have a certain amount of clearance within the slot to enable it readily to be inserted. Accordingly, the driver has a substantial amount of angular play within the slot in its two directions of turning. This angular play results in point contacts between-the driver and the walls of the screw slot while driving, the two opposite forward points or edges of the driver being in contact with corresponding surfaces of the slot. This type of point contact tends to wear down and round off the driving edges and points on the driver and results in a component of force tending to push the driver out of the slot. 1

Attempts have been made to overcome this usual tendency of a driver to be forced out of a slot while driving. One expedient, for example, has been to undercut the slot somewhat to overcome the, effect of an outward component of force pushing the driver out. Such undercutting,'however, has not overcome the undesired point contacts of the driver within the slot walls. An attempt has even been made to make the base of the slot arcuate so that the deepest part of the slot is at the center of the screwhead and the shallowest is at the sides. This expedient, however, even when combined with ordinary undercutting at the center, does not provide more'than point contact.

As fully set forth in the aforementioned U. S. patents, the disadvantages of the previous types of slotted screw heads have been overcome by the provision of a unique form of slot wherein contact between the driver and the slot walls is had over a substantial surface area of the slot walls, rather than merely at points or edges.

This novel slot has an arcuate base and diverges out? wardly from the center. Furthermore, it is undercut at the sides where the driving torque is applied, though not at the center. As also set forth in the aforementioned patents, the slot can conveniently be made with a milling cutter having diverging peripheral edges by twisting or turning the'milling cutter about a diametric axis through a slight angle from either side of the longitudinal axis of theslot. It follows that in order to provide substantially full surface contact between such a slot and a screw driver to be used therewith, the peripheral driving edge of the driver should have opposite side surfaces of'similargeometric configuration to the milling cutter employed in initially making the slot. 8

Accordingly, the present invention has as its primary object the provision of a screw driver in which full surface contact is attained between the slot walls and vthe opposite side driving surfaces of the driver.

Another important object is to provide a screw driver in the form of a driving disc having a three hundred sixty degree peripheral edge of given transverse width, any circumferential edge portion of which is adapted to fit into the slot in a screw headwhereby after one portion of a peripheral driving edge has become worn or damaged, an other circumferential portion may be employed by simply rotating the disc slightly.

Still another object is to provide a screw driver employing adriving disc of the above type including, in combination, a holding means having one end secured to the disc and the other end extending radially away therefrom whereby the holding means may be swung ninety degrees from a vertical position in the plane ofthe disc to a horizontal position whereby turning of a screw with very high torque may be effected by then rotating the entire holding means in a horizontal plane about a vertical.

diametric axis, of the disc.

Still another object is to provide a holding means for a disc driver such as set forth above including a retaining head which may be interchanged whereby diiferent diameter discs may be employed for different slot dimensions and in which different circumferential peripheral:

driving edges may be brought into position for easycooperation with the slotted portion of a screw head.

These and many other objectsand advantages of the present invention are attained by providing a driving portion terminating in a peripheral edge having opposite side surfaces which diverge from each other towards said edge, these side surfaces being conical surfaces of revolution. In a preferred embodiment, the driving portion is in the form of a driving disc having a three hundred sixty degree peripheral edge of given transverse width, the opposite side surfaces of the disc adjacent-the peripheral edge diverging radially outwardly towards the edge from a circumferential line spaced radially inwardly from the edge to define the referred to conical surfaces of revolution. Thus, the transverse thickness of the disc at thecircumferential line is less than the transverse width of the disc at its outer edge. An elongated holding means is arranged to co-operate with the disc and secure the' disc at one end, the other end of the holding means eX-- tending radially away from-the disc so that. the disc may be rotated about one of its diametric axes after a peripheral portion of its edge has been inserted in the slot of the screw head.

The holding means itself includes aretaining head hav- I the portions of the retaining head separated by the slot. The disc itself is provided with a central hub on each The slot is ofav 'width sufficient to receive the transverse width of the driving disc such that its opposite sides are straddled by q side adapted to seat against the end shoulders defined by the termination point of the bore within the retaining head, and a set screw or the like may be provided to bear against a peripheral portion of the disc to secure it within the slot. By this arrangement, the disc may be rotated within the retaining head by simply loosening the set screw and resetting the same whereby a new peripheral driving edge portion may be readily positioned for use.

Preferably, the holding means also includes an elongated shaft having a square block at one end adapted to be received in a squareusocket in the retaining head, the other end of the shaft terminating in a handle. The shaft and handle extend radially away from the disc such that the conventional type rotation of the handle will rotate the disc about one of its diametric axes. Alternatively, the handle may be swung downwardly in the plane of the disc through an:angle of ninety degrees whereby a peripheral portion of the disc ninety degrees displaced from the original slot engaging peripheral portion will now engage the slot in the screw head. Swinging of the handle in a horizontal plane may then be efiected to provide a greatly increased torque for driving the screw. The feature of a simple socket receiving connection for the retaining head with the shaft enables other retaining heads and discs of different dimensions to be readily used with the same shaft and handle.

A better understanding of the invention willbe had by referring to the accompanying drawings, in which:

Figure l is a perspective view of the basic screwdriving disc of the present invention including a schematic projected surface portion useful in explaining the configuration of the driving disc;

Figure 2 illustrates in perspective a preferred holding means for securing the driving disc of Figure 1;

Figure 3 is a side elevational view partly cut away showing the holding means and driving disc assembled for use;

Figure 4 is another elevational view of the driver, partly cut away, taken in the, direction of the arrows 44 of Figure 3; a

Figure 5 is a perspective view of a slotted screw head with which the screw driver of the present invention is employed; and,

Figure 6 is a schematic illustration of one manner of operating the screw driver of this invention.

Referring to Figure 1, there is illustrated a basic component of the screw driver in the form of a driving disc having a peripheral edge 10 extending completely around in a circle for three hundred sixty degrees. The transverse width of the edge 10 is indicated in Figure l at w and is dimensioned to be received within the slot of a screw head with which the driving disc is employed. As shown in Figure l, the opposite side surfaces of the disc adjacent the peripheral edge 10, such as the surface 11, diverge radially outwardly towards the edge from a circumferen tial line indicated at c spaced radially inwardly from the peripheral edge, to define non-planar conical surfaces of revolution. From the circumferential line c, the side surfaces diverge to the normal thickness of the disc merging into flat face surfaces such as indicated at 13 at the center portion of which are provided hubs such as hub 14. The transverse thickness of the disc at the circumferential line 0 is therefore less than the given transverse width w.

The reason why the side surfaces, such as the surface 11, are defined as non-planar conical surfaces of revolution will be apparent by referring to the projected portion of this surface along the disc axis A-A of Figure l as indicated at 11'. Note that if radially directed lines are drawn at an inclination defined by the diverging characteristic of the surface, such lines will intersect the A- A axis at the point P which constitutes the apex of a cone. The surface 11' is thus a conical surface of revolution and is non-planar since the various radially directed lines converging at the point P do not lie in-a single plane yet constitute straight lines which lie on diiferent portions at the surface 11.

As mentioned heretofore, the slot in the screw head with which the present invention is employed is generated by means of a milling cutter having diverging peripheral opposite side surfaces in the form of conical surfaces of revolution, as fully set forth in applicants aforementioned Patent Number 2,745,120. Thus, by making the opposite side surfaces, such as the surface 11, of the driving disc of the same geometric configuration, the sidewalls of the slot structure will be fully engaged by the driver.

Referring to Figure 2, a holding means for enabling convenient manual operation of the driving disc is illustrated as comprising a retaining head 15 having a bore 16 passing from one face into the head and terminating within the head as at 17. The retaining head 15 is also provided with a slot passing from the same front face as the bore 16 and extending into the head in a plane including the axis of the bore to terminate at a point 19 beyond the termination point 17 of the bore. The retaining head 15 also includes a locking means in the form of a set screw 20 passing into: a side face thereof to intersect the slot 18 adjacent its termination point 19, as will become clearer with reference to Figures 3 and 4. The remaining portion of the holding means of Figure 2 comprises an elongated shaft 21 secured to the retaining end 15 at one end and terminating in a handle 22 at its other end.

Referring to Figure 3, the holding means of Figure 2 and driving'disc of Figure 1 are shown in assembled side view. Preferably, the end of the elongated shaft 21 secured to the retaining head 15 terminates in a square block 23 receivable in a square socket 24 formed in the retaining head 15. A conventional spring biased detent ball 25 may be provided inthe block 23 for temporarily securing the shaft 21 with respect to the socket 24. In Figure 3 the extent of the bore 16 is indicated in dotted lines.

In the broken away portion of the elevational view of Figure 4, the manner in which the driving disc is secured within the retaining head 15 is clearly illustrated. As shown, the termination portion of the bore 17 has a corresponding portion 17a against which the hub 14 seats. The other side hub 14a of the disc is shown seated against the .bore termination part 17. Also shown in Figure 4 are the opposite side surfaces 11a for the surface 11 and 12a for the surface 12. It will be noted in Figure 4 that the set screw 20 passes into the side of the retaining head 15 at a slight angle such that the end of the set screw will besubstantially flush with the diverging surface 11 adjacent the periphery of the disc. This set screw 20 will lock the disc against inadvertent rotation within the slot 18 of the retaining head. In the event, however, it is desired to provide a fresh peripheral driving portion for engagement with the slot in the screw, it is a simple matter to loosen the set screw 20 and rotate the disc a few degrees and then re-tighten the set screw.

In Figure 5 there is shown in perspective a slotted screw head 26 having a transverse slot 27 with slot edges diverging towards the periphery of the screw head. The bottom of the slot 27 is arcuate as indicated at 28, the radius of curvature of the are 28 corresponding to the radius of the driving disc portion of the screw driver. Also shown in Figure 5 are the undercut side walls 29 for the screw head. A more complete description of this slotted'screw head is set forth in applicants aforementioned Patent Number 2,677,985 wherein the undercut side walls 29 are defined as non-planar conical surfaces of revolution. It will be evident, therefore, that the opposite peripheral side surfaces 11 and 11a will engage in complete surface contact the undercut side walls 29 of the screw when the driving disc is inserted therein as indicated in Figure 6.

Referring to Figure 6, one manner of actually driving the screw head 26 is illustrated in dotted lines at 22' wherein the elongated holding means constituting the handle 22 and shaft 21 has been swung ninety degrees in the plane of the disc to a horizontal position whereby it may then be turned in a horizontal plane as indicated by the arrows 30 to enable a very high torque to be applied to the screw head.

The operation of the improved screw driver of this invention will be evident from the foregoing description with respect to the accompanying drawings. The width of the slot in the screw head corresponds to the transverse width w of the driving disc peripheral edge such that any circumferential portion of the disc may be readily inserted in the slot 27 of the screw as shown in Figure 5. After a peripheral edge portion has been inserted in the slot, a slight rotation of the disc by rotating the handle 22 to turn the disc about one of its diametric axes will cause the non-planar conical surfaces of revolution 11 and 11a to engage the undercut sidewalls 29 in complete surface contact so that the edge of the driving disc cannot now be lifted out of the slot. As continued turning torque is applied to the driving disc about one of its diametric axes, the undercut design of the slot in co-operation with the diverging opposite side surfaces of the disc tend to cam the driving edge of the disc into even tighter engagement in the slot whereby very high torques may be applied to the slotted screw head without possibility of disengagement of the driving disc from the slot. By initially inserting a side portion of the peripheral portion of the disc in the slot with the driving handle 22 in the horizontal position 22 shown in Figure 6, or alternatively by simply rotating the disc edge within the slot ninety degrees to the position shown in dotted lines in Figure 6, and then rotating the entire handle assembly in a horizontal plane as described heretofore, an extremely high torque may be applied to the screw head.

It will also be clear that any circumferential portion of the entire periphery of the disc may be employed for engaging the slot and thus if some portions become worn, other new unused portions may be positioned by loosening the set screw as described heretofore and repositioning the disc in the retaining head 15. Additionally, other sized discs with correspondingly designed retaining heads, all provided, however, with the same sized socket, may be readily substituted for use with the same shaft 21 and handle 22.

Many modifications falling within the scope and spirit of the screw driver of this invention will readily occur to those skilled in the art. The invention is, therefore, not to be thought of as limited to the particular embodiment disclosed in the drawings for illustrative purposes.

What is claimed is:

1. A screw driver comprising, in combination: a driving disc having a three hundred and sixty degree peripheral edge of given transverse width, the opposite side surfaces of said disc adjacent said peripheral edge diverging radially outwardly towards said edge from a circumferential line spaced radially inwardly from said edge to define. non-planar conical surfaces of revolution, the transverse thickness of said disc at said circumferential line being less than said given width; an elongated holding means including at one end a retaining head having an axial bore passing from one face thereof and terminating within said head, said head including a slot passing into said face diametrically through said bore in a plane including the axis of said bore, said slot terminating at a point in said head spaced beyond the termination of said bore, whereby the termination point of said bore defines end shoulders, said slot having a width suflicient to receive said transverse width of said driving disc; said driving disc including hub portions extending transversely from the opposite center surface portions of said disc, adapted to abut against said end shoulders when said disc is positioned in said slot; and set screw means passing transversely into a side face of said retaining head to intersect said slot adjacent its point of termination and bear against a side of said disc to retain said disc in said head, the other end of said holding means extending radially away from said disc, whereby said disc may be rotated about one of its diametric axes.

2. A screw driver according to claim 1, in which said retaining head includes a square socket on its face op posite said one face, said holding means including an elongated shaft terminating at one end in a square block receivable in said socket, and at its other end in a handle.

3. A screw driver comprising, in combination: a driving disc having a three hundred sixty degree peripheral edge of given constant transverse width, the opposite side surfaces of said disc adjacent said peripheral edge diverging radially outwardly towards said edge from a circumferential line spaced radially inwardly from said edge to define non-planar conical surfaces of revolution, the transverse thickness of said disc at said circumferential line being less than said given transverse width; an elongated holding means including at one end a retaining head, said retaining head having a slot extending in a plane including the longitudinal axis of said elongated holding means, said slot terminating within said head and having a width sufficient to receive the transverse width of said driving disc; and set screw means passing transversely into a side face of said retaining head to intersect said slot adjacent its point of termination and bear against a side of said disc between said circumferential line and said edge to retain said disc in said head.

References Cited in the file of this patent UNITED STATES PATENTS 1,230,173 Kremer June 19, 1917 1,249,394 Hess Dec. 11, 1917 2,631,623 West Mar. 17, 1953 2,808,087 Vaughn Oct. 1, 1957 FOREIGN PATENTS 125,321 Great Britain Apr. 17, 1912 

